Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of early myeloid progenitors/precursors of granulocytes, macrophages and dendritic cells. These cells are commonly characterized by the expression of the myeloid lineage markers, Gr-1 and CD11b. MDSCs play a critical role in tumor immune escape mechanisms, autoimmune diseases, transplant rejection, chronic inflammation, and infection, by suppressing T-cell effector functions via up-regulating the expression of immunosuppressive factors, such as arginase 1 (ARG-1) and nitric oxide synthase 2 (NOS2). See, e.g., Gabrilovich and Nagaraj, Nat Rev Immunol 9:162-174 (2009).
Due to their immunosuppressive properties, MDSCs are promising candidates for treating immunological diseases. Thus, there is a need for stable and safe MDSCs generated ex vivo.